There’s a new darling among the exercise-to-exhaustion crowd: the VersaClimber, a device that simulates a vertical crawl on a ladder. Athletes, including LeBron James, swear by it. And group fitness classes, such as Rise Nation, are opening around the country. “It’s a great solution if you’re injured or looking to minimize impact and for those who love the pain cave,” says Eric Dannenberg, a performance manager at Exos, a training and exercise research company.

The machine is powered by only your movement, so you control the stride and speed. It’s what makes the VersaClimber so safe—it goes as fast as you move. Plus, it’s nearly impossible to screw up form, and there’s minimal impact on joints.

Fitness on the Fly: VersaClimber Fat Loss Intervals

For some, the best part is how little time it takes to get in a workout; about 10 minutes is the magic number, says Tim Anderson, a co-founder of Original Strength Systems in North Carolina. In that short time, the VersaClimber taxes your heart, lungs, and muscles. It even exercises your brain.

To start, adjust the handles into the pegs so they’re at shoulder height. Strap into the foot pedals, and start your contralateral climb (left hand rises with right foot, and right hand rises with left foot). There’s no learning curve, but those first couple of sessions are a doozy. “It may be one of the hardest machines you’ve ever been on, but it will get easier,” Anderson says.

He recommends breath control for better endurance. For instance, keep your tongue resting against the roof of your mouth, which activates the diaphragm. When you’re more comfortable on the climber, try inhaling and exhaling only through your nose to stay relaxed during the strenuous session.

Add in the VersaClimber three to four times a week, but not much more than that. “You won’t get the best results going max effort every time, since it can lead to injury and burnout,” Dannenberg says. A lot of people have a love-hate relationship with the VersaClimber, so we’re guessing you’ll miss it on your days off.